Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H,W=map(int,input().split())
MAP=[list(input()) for i in range(H)]


ANS=0
for i in range(H):
    ANS+=MAP[i].count(".")

from collections import deque

QUE = deque()
QUE.append((0,0))
MAP[0][0]=0

while QUE:
    (x,y)=QUE.pop()

    for i,j in [(x+1,y),(x-1,y),(x,y+1),(x,y-1)]:
        if i<0 or j<0 or i>=H or j>=W:
            continue
        if MAP[i][j]==".":
            MAP[i][j]=MAP[x][y]+1
            QUE.appendleft((i,j))
            
        
if MAP[H-1][W-1]==".":
    print(-1)
else:
    print(ANS-MAP[H-1][W-1]-1)